Measurement of Steam-Generator Tube Damping Caused by Anti-Vibration-Bar Supports
Bibliographic record
Abstract
Abstract In 2013, Atomic Energy of Canada Limited (now Canadian Nuclear Laboratories) took vibration measurements to examine low-frequency damping associated with tube vibration parallel to anti-vibration bar supports. These tests were performed to better understand and control in-plane fluidelastic instability of tubes in the U-bend region of recirculating steam generators. In the tests, the damping ratios of a single steam generator tube vibrating parallel to a single pair of anti-vibration bars were measured using both a log-decrement and a power-based method. Non-contacting excitation and position-sensing techniques were employed to improve accuracy. The tests examined the effects of fluid (water or air), natural frequency, gap width, preload, and vibration normal to the bars. Additional tests were also done using a drilled-hole support and without supports to allow validation against previously published work. Most of the tests were performed in water. This paper describes the tests including the test apparatus, test methods, and analysis techniques. A summary of the results is presented. These results show that the damping ratios measured without any supports and with a drilled-hole support are consistent with previously published data. Contrary to an existing design guideline, the anti-vibration bars resulted in no significant additional viscous or squeeze-film damping for vibration parallel to the bars. The results also showed that anti-vibration bars can introduce significant in-plane Coulomb-type damping because of friction and impacting.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".